The following abbreviations and terms are herewith defined, at least some of which are referred to within the following description of the present disclosure.
3GPP 3rd-Generation Partnership Project
AGCH Access Grant Channel
ASIC Application Specific Integrated Circuit
BLER Block Error Rate
BSS Base Station Subsystem
CC Coverage Class
CN Core Network
DRX Discontinuous Receive Cycle
EC-GSM Extended Coverage Global System for Mobile Communications
EC-PCH Extended Coverage Paging Channel
eDRX Extended Discontinuous Receive
eNB Evolved Node B
DL Downlink
DSP Digital Signal Processor
EDGE Enhanced Data rates for GSM Evolution
EGPRS Enhanced General Packet Radio Service
GSM Global System for Mobile Communications
GERAN GSM/EDGE Radio Access Network
GPRS General Packet Radio Service
HARQ Hybrid Automatic Repeat Request
IMSI International Mobile Subscriber Identity
IoT Internet of Things
LTE Long-Term Evolution
MCS Modulation and Coding Scheme
MME Mobility Management Entity
MS Mobile Station
MTC Machine Type Communications
NB Node B
PCH Paging Channel
PDN Packet Data Network
PDTCH Packet Data Traffic Channel
PDU Protocol Data Unit
PLMN Public Land Mobile Network
RACH Random Access Channel
RAN Radio Access Network
RAT Radio Access Technology
RAU Routing Area Update
SGSN Serving GPRS Support Node
TDMA Time Division Multiple Access
TS Technical Specifications
UE User Equipment
WCDMA Wideband Code Division Multiple Access
WiMAX Worldwide Interoperability for Microwave Access
Coverage Class (CC): At any point in time a wireless device belongs to a specific uplink/downlink coverage class that corresponds to either the legacy radio interface performance attributes that serve as the reference coverage for legacy cell planning (e.g., a Block Error Rate of 10% after a single radio block transmission on the PDTCH) or a range of radio interface performance attributes degraded compared to the reference coverage (e.g., up to 20 dB lower performance than that of the reference coverage). Coverage class determines the total number of blind transmissions to be used when transmitting/receiving radio blocks. An uplink/downlink coverage class applicable at any point in time can differ between different logical channels. Upon initiating a system access a wireless device determines the uplink/downlink coverage class applicable to the RACH/AGCH based on estimating the number of blind transmissions of a radio block needed by the BSS (radio access network node) receiver/wireless device receiver to experience a BLER (block error rate) of approximately 10%. The BSS determines the uplink/downlink coverage class to be used by a wireless device on the assigned packet channel resources based on estimating the number of blind transmissions of a radio block needed to satisfy a target BLER and considering the number of HARQ retransmissions (of a radio block) that will, on average, be needed for successful reception of a radio block using that target BLER. Note: a wireless device operating with radio interface performance attributes corresponding to the reference coverage (normal coverage) is considered to be in the best coverage class (i.e., coverage class 1) and therefore does not make any additional blind transmissions subsequent to an initial blind transmission. In this case, the wireless device may be referred to as a normal coverage wireless device. In contrast, a wireless device operating with radio interface performance attributes corresponding to an extended coverage (i.e., coverage class greater than 1) makes multiple blind transmissions. In this case, the wireless device may be referred to as an extended coverage wireless device. Multiple blind transmissions corresponds to the case where N instances of a radio block are transmitted consecutively using the applicable radio resources (e.g. the paging channel) without any attempt by the transmitting end to determine if the receiving end is able to successfully recover the radio block prior to all N transmissions. The transmitting end does this in attempt to help the receiving end realize a target BLER performance (e.g. target BLER≤10% for the paging channel).eDRX cycle: eDiscontinuous reception (eDRX) is a process of a wireless device disabling its ability to receive when it does not expect to receive incoming messages and enabling its ability to receive during a period of reachability when it anticipates the possibility of message reception. For eDRX to operate, the network coordinates with the wireless device regarding when instances of reachability are to occur. The wireless device will therefore wake up and enable message reception only during pre-scheduled periods of reachability. This process reduces the power consumption which extends the battery life of the wireless device and is sometimes called (deep) sleep mode.Extended Coverage: The general principle of extended coverage is that of using blind transmissions for the control channels and for the data channels to realize a target block error rate performance (BLER) for the channel of interest. In addition, for the data channels the use of blind transmissions assuming MCS-1 (i.e., the lowest modulation and coding scheme (MCS) supported in EGPRS today) is combined with HARQ retransmissions to realize the needed level of data transmission performance. Support for extended coverage is realized by defining different coverage classes. A different number of blind transmissions are associated with each of the coverage classes wherein extended coverage is associated with coverage classes for which multiple blind transmissions are needed (i.e., a single blind transmission is considered as the reference coverage). The number of total blind transmissions for a given coverage class can differ between different logical channels.Internet of Things (IoT) devices: The Internet of Things (IoT) is the network of physical objects or “things” embedded with electronics, software, sensors, and connectivity to enable objects to exchange data with the manufacturer, operator and/or other connected devices based on the infrastructure of the International Telecommunication Union's Global Standards Initiative. The Internet of Things allows objects to be sensed and controlled remotely across existing network infrastructure creating opportunities for more direct integration between the physical world and computer-based systems, and resulting in improved efficiency, accuracy and economic benefit. Each thing is uniquely identifiable through its embedded computing system but is able to interoperate within the existing Internet infrastructure. Experts estimate that the IoT will consist of almost 50 billion objects by 2020.Cellular Internet of Things (CIoT) devices: CIoT devices are IoT devices that establish connectivity using cellular networks.Nominal Paging Group: The specific set of EC-PCH blocks a device monitors once per eDRX cycle. The device determines this specific set of EC-PCH blocks using an algorithm that takes into account its IMSI, its eDRX cycle length and its downlink coverage class.MTC device: A MTC device is a type of device where support for human interaction with the device is typically not required and data transmissions from or to the device are expected to be rather short (e.g., a maximum of a few hundred octets). MTC devices supporting a minimum functionality can be expected to only operate using normal cell contours and as such do not support the concept of extended coverage whereas MTC devices with enhanced capabilities may support extended coverage.
Work is currently ongoing within the 3GPP to specify a cellular radio access technology (RAT) which is dedicated to catering to the so-called Internet of Things (IoT) market. One study is ongoing in 3GPP GSM GERAN, but similar studies are also ongoing in 3GPP RAN for both Wideband Code Division Multiple Access (WCDMA) and Long-Term Evolution (LTE).
One important objective of these studies is to handle a vast number of Machine Type Communication (MTC) wireless devices where some of the MTC wireless devices (e.g., IoT devices, CIoT devices) might be situated in areas of extreme radio coverage. In addition, many of the MTC devices are considered to be stationary, i.e., the MTC devices are not moving around in the wireless communication network.
One of the candidate solutions proposed within the framework of the ongoing 3GPP GERAN study is the Extended Coverage Global System for Mobile Communications (EC-GSM) solution. In EC-GSM, the extended coverage is achieved via a repetition-based transmission scheme (i.e., blind transmission scheme) wherein N instances of a radio block are transmitted consecutively regardless of whether the receiving end is able to successfully recover the radio block prior to all N transmissions (i.e., a transmitter is said to blindly transmit a radio block if it does so without any concern about whether the receiver is able to receive the radio block prior to the Nth transmission).
Depending on the actual coverage for a wireless device (e.g., MS, UE, MTC wireless device, IoT device, CIoT device), a different number of repeated (blind) transmissions will be needed in order to successfully establish the needed connection and sustain ongoing data transmissions with the wireless device. Different coverage classes are therefore defined, where a coverage class (CC) of a wireless device indicates what radio coverage the wireless device is experiencing and, thus, how many blind transmissions would be needed to reach the wireless device according to a target BLER. The wireless devices which are within coverage that is in parity with what is supported by legacy General Packet Radio Service (GPRS) radio network systems are considered to be in normal coverage (Coverage Class 1 (CC1)).
An example of when specific measures are needed in order to achieve an extended coverage is when a paging message is to be transmitted to a wireless device. In order to successfully transmit the paging message to the wireless device with an acceptable BLER, in the cell in which the wireless device is located, and thus listening to its nominal paging group, the paging message is repeated a number of times corresponding to the coverage class (CC) of the wireless device.
Work is also ongoing within 3GPP to decrease the power consumption of a wireless device (e.g., MS, UE, MTC wireless device, IoT device, CIoT device). One mechanism to decrease the power consumption is to let the wireless device listen to the paging channel (e.g., for possible paging message reception) less frequently based on using an extended Discontinuous Receive (eDRX) cycle, with paging cycle lengths in the area of tens of minutes being discussed. The latency when trying to reach the wireless device is thus increased correspondingly. In case the paging procedure is not successful, e.g., due to paging message(s) being sent in cells where the targeted wireless device is not currently located, the paging capacity requirements will increase significantly as these paging messages will consume paging channel bandwidth while the targeted wireless device is not present to listen to these paging channels.
In order to limit the amount of radio resources used for paging, a mechanism (i.e., the mobility history mechanism) has been proposed to 3GPP whereby the network keeps track of the location of a wireless device in an area of a few cells. This is achieved by using a so-called mobility history list, which is a list of the cells last visited by the wireless device. The mobility history list is stored (maintained) both in the wireless device and in the network (e.g., a CN node such as an SGSN), and the list is updated by the wireless device performing a Cell Update every time the wireless device enters a cell that is not part of the mobility history list (i.e., a wireless device uses the Cell Update procedure to convey mobility history to the network). This enables the network to reach the wireless device with a paging message while only transmitting paging messages in a few cells and thereby dramatically reducing the demand for paging channel capacity.
One problem with the mobility history list mechanism is that a wireless device with high mobility will need to transmit many Cell Updates in order to keep the wireless device's list up to date. This will have a negative impact on the power consumption of the wireless device and the availability of packet channel resources in the serving wireless communication system.
A possible solution to this problem that has been proposed is for the network to deactivate the use of the mobility history list for a given wireless device when detecting that the wireless device is transmitting too many Cell Updates. However, this solution would allow for a wireless device with high mobility to first perform a number of Cell Updates prior to the determination that the mobility history list should not be used for that wireless device. In addition, this solution would be repeated every time the wireless device is restarted or if the wireless device enters an area of another network node, e.g., when performing a Routing Area Update (RAU). Accordingly, there is still a need to address the aforementioned shortcomings associated with the current mobility history list mechanism. This need and other needs are addressed by the present disclosure.